Every year, a large percentage of medicines (including prescription and over-the-counter) sold remain unused in households or hospitals, are recalled or become expired. For example, in one county (King county, WA) in the U.S., the amount of unused household medicines adds up to about 11 million containers per year. Unwanted medicines that aren't properly disposed of end up in the environment. Currently, the two main modes of disposing of unused medicines are by flushing them down the toilet or throwing them in trash. Both of these methods contribute to the contamination of soil and the underground or surface water supplies. Wastewater treatment processes do not remove pharmaceuticals contained in medicines. Most pharmaceuticals are not biodegradable and thus exposure to air or sun in landfills does not deactivate or degrade them. As the results, these chemicals accumulate in the environment and in aggregate can be hazardous to the environment and human health. For instance, an Associate Press investigation has found that in 24 major metropolitan cities (hosted.ap.org/specials/interactives/pharmawater_site/) in the U.S. the drinking water supplies of at least 46 million people are contaminated with minute amounts of many pharmaceuticals. Some of frequently detected pharmaceuticals in this investigation were atenolol (heart medication), carbamazepine (for seizure), gemfibrozil (anti-cholesterol), meprobamate (tranquilizer), naproxen (over-the-counter pain reliever), phenytoin (anti-seizure medication), sulfamethoxazole and trimethoprinm (antibiotics).
At the moment, there is no way of knowing what impact low levels of pharmaceuticals will have on human health. However, there is no doubt that a cumulative effect of so many different drugs (including anti-psychotic drugs, antibiotics, pain medications, heart and circulation drugs, contraceptive drugs, diabetes drugs, and chemotherapeutic or anti-proliferative drugs) can have adverse effect on human health. Therefore, there remains a need for a safe and proper disposal of medicines.